Laying out Rear Spar

[DesertBearhawk]

Guys, I am laying out the rear spar. Locating the critical holes in the cap strips. I worked over the plans and made my measurements carefully. Then I laid the cap strip onto of the finished rear spar (the left spar in this case) and started to look at how things were lining up. What I am finding is the rib locations are not lining up perfectly. They are off between 1/8th and 3/16ths. I know this is a game of a fraction of an inch and the plans give 1/32 tolerance but I want to get things right. I am not above admitting that I may have mad some minor errors in measurements on the main spar (nothing huge but a 16th here and a 16th there adds up) so, would the way to proceed be to line up the rib centerlines (my assumption is YES)? Assuming that is the case should I locate the hinges as per the plans or work my measurements off the rib locations. Again, I think going with the plans to locate the hinges is the right move...

I hope you understand the question I am asking….

So, What say you?

[X'N]

Could you offset your ribs using a longer (meaning the C/L of the rivets to the outside edge where the rib attaches) rib attach angle or maybe also shorter?

[DRLPatrol]

I have a dumb question along these lines. When the drawings call out rib locations, are they measured to face/web of the rib or rivet line.
Doug

[bestbearhawk1231]

Doug, I am using the rivet line of the rib as the centerline when I drill the spars for the attach angles. I did it this way on both ailerons and flaps so far. If they turn out ok ( I am sure they will) then I will be using this same method on the wings themselves. I thought I read that somewhere but I can't find where it was.

[marcusofcotton]

Doug,
On the four place plans page 3 it is illustrated to use the rivet line.
Mark J

[bestbearhawk1231]

That is where I read it!

[DRLPatrol]

Thanks, I'll look again but I sure did not see it on my patrol plans.

[marcusofcotton]

Dave,
​When doing construction, I found that spending more time being anal about measurements, plumb, and square during foundation and rough in saved a lot of time and bother later when finishing. Similar here but it can work out fine. I'd make the rear line up with the front so all are parallel and have your hinge placements follow your new spacing. It will mean more careful thought about what follows and where to place but shouldn't be too bad.

Mark J